1. Field of the Invention
The present invention relates to novel 1-OH-2-acyl-sn-glycero-3-phosphocholine compounds and its analogs, pure or mixed, having formula WCH2CHXCH2PO3YCH2CH2Z, where W is preferably a hydroxyl group or an O-acyl group containing from 2 to 22 carbon atoms, and where X is preferably an O-acyl group containing from 2 to 22 carbon atoms or a hydroxyl (OH) and where Y may be an (O−) or OH and where Z is preferably a trimethyl-ammonium group [N+(CH3)3] can be protonated dimethyl ammonium [N+H(CH3)2] group. In the O-acyl groups containing 18 carbon atoms can be observed from 0 to 3 instaurations, useful as biocidal agents; processes for their preparation; and antifouling compositions, preferably paints useful in susceptible fouling surfaces, such as hulls of vessels.
The present invention is also directed to methods to turn a surface into an antifouling surface, to a method to prevent fouling and to the antifouling surfaces comprising a coating of the said antifouling composition.
The present invention applies to the industrial technical field of coatings and paints for underwater protection, against harmful effects of biofouling, of submerged or floating structures in fresh or salt water, e.g., hulls of vessels, buoys, oil platforms and ducts/pipes. Such product may be added to the coating material by directly dispersion, by forming chemical bonds, incorporated by microencapsulation or combination of these means.
2. Prior Art
The present invention was motivated by the global issue related to the prohibition of use, adopted on 5 Oct. 2001 by the International Maritime Organization (IMO) and promulgated on 17 September 2008, of the compound known as tri-butyl tin (TBT), major and most effective biocide used in marine coatings and antifouling paints (IMO, 2010; GIPPERTH, 2009), and also believing that the use of a biocide/repellent based on natural compounds is indeed the best answer for the replacement of TBT in the fight against marine biofouling.
The present invention is justified by the need for the existence of commercial products with antifouling biocide/repellent action, not environmentally friendly, of easy synthesis, which involves the use of a cheap and abundant raw material associated with a synthetic route easy to perform, which can be used in the preparation of coatings and antifouling marine paints.
Biofouling
Biofouling is a natural process that occurs with any structure placed in contact with water where there is the presence of micro-organisms. It begins immediately after the object was placed in the sea, by the adhesion of organic substances and materials dissolved in water, developing into a situation where there is the presence of marine macro-organisms such as algae, barnacles and mussels (CALLOW and CALLOW, 2006; BHADURY and WRIGHT, 2004; YEBRA et al., 2004).
Problems due to the presence of biofouling are comprehensive, ranging from the clogging of pipes, through the structural impairment of platforms and reaching the harmful action of the performance of vessels by increasing the drag force. From a military standpoint, the growth of fouling on the hulls of vessels is considered a serious and routine problem, due to the fact that decrease the final speed of the vessel and its maneuverability, blocking cooling windows, increase fuel mileage and compel the dockings or more frequent assets, contributing to the potential failure of any military action.
Technically the process of biofouling consists of four stages, not strictly sequential, but interdependent. The first stage begins in the first minutes of contact with the water surface, when occurs the accumulation of organic molecules such as polysaccharides and proteins. This allows, in the coming hours (24-96 h), the development of early colonization by bacteria, e.g. Pseudomonas, Leptothrix, Rhodopseudomonas, Desulfovibrio, Beggiatoa, and diatomaceus, e.g. Navicula e Nitszchia, which together with cyanobacteria, e.g. Phormidium and Oscillatoria, protozoa and rotifers, which exude different polysaccharides, called exopolysaccharides, which in a complex mixture with nucleic acids, proteins, minerals, nutrients, cellular debris and micro-organisms themselves, form the second stage which is called by biofilm (CALLOW and CALLOW, 2006; BHASKAR and BHOSLE, 2005; ARCE et al., 2004).
The presence of biofilm allows micro-organisms have greater protection from predators, toxins and environmental changes, and allows adequate availability of nutrients, seized of the marine environment, which are dispersed in this biofilm. This designation, biofilm, it must not be understood in the strict sense of the word, because in fact the same is not presented as a continuous or homogeneous layer, or as a foil (film), and its structure, heterogeneous in space and time, changing due to external and internal processes (DONLAN, 2002; COSTERTON, et al. 1994). In fact, its structure has, more often, communities of grouped micro-organisms called clusters, having canalith that permit the passage of water bringing nutrients, oxygen, and therefore other possible compounds such as biocides (DONLAN, 2002; DUNNE, 2002; SUTHERLAND, 2001; DAVEY e O'TOOLE, 2000). The formation of a cluster begins with the contact and adhesion of bacteria to an etched surface, forming a small colony that grows due to the multiplication of micro-organisms and the accumulation of exudates exopolysaccharides, and may acquire formats ranging from the mounds to structures like mushrooms, reaching a state of maturity where it initiates an active process of dispersion that allows the formation of new colonies (STOODLEY, et al. 2004; LASPIDOU, 2003; LOOSDRECHT, et al. 1990). The exopolysaccharides are the main compounds of the dehydrated biofilm, accounting for between 50% and 90% of total organic carbon present in it, but when fully hydrated, the water can reach 97% of its weight. They may vary in their physical and chemical properties, but usually consist of heteropolymerics polysaccharides with molecular weight of the order of kiloDaltons, which, due to the type of monosaccharides based on their training e.g. glucuronic acids, galacturonic, manuranico, etc., are generally anionic, casually neutral and rarely positively charged, having hydrophilic and hydrophobic regions. Although alone they form various types of structures within the biofilm, these polysaccharides can interact with other types of molecules such as proteins and lipids, forming what is known as extracellular polymeric substances (EPS) (BHASKAR and BHOSLE, 2005; PARSEK and FUQUA, 2003; DONLAN, 2002; SUTHERLAND, 2001; DeBEER e KOHL, 2001; ALLISON, 1998).
The third stage is the secondary colonization made by macroalgae spores, larvae of barnacles, fungi, protozoa and other bacteria, which transform the biofilm during the first week in a more complex composition.
The fourth stage involves the settlement, and especially the growth of marine macro-organisms such as molluscs, bryozoans, antozoans, polychaetes, tunicates and crustaceans (FLEMMING et al., 1996; BORENSTEIN, 1994).
The type, the extent and the severity of biofouling depends on the factors such as substrate type, water salinity, ambient light, temperature, pollution and available nutrients. Thus, biofouling tends to be a seasonal phenomenon related to geographical location. In polar regions, with temperatures below 5° C., the action of biofouling is low, in temperate zones (5 to 20° C.), the risk is medium, while in tropical and subtropical zones, where temperatures are greater than 20° C., the risk associated with biofouling is high, mainly due to the suitable condition for multiplication of fouling organisms, which is estimated there are over 4000 species with potential to colonize submerged surfaces (PROPELLER, 2004).
Thus, ships that travel or remain in tropical or subtropical areas are subject to more severe attacks by biofouling, particularly in shallow or coastal waters, where there is a greater availability of light, heat and nutrients, e.g. Guanabara Bay, R J.
Control of Biofouling on Ships
The search for products that work effectively as a biocide in vessel paint, dates from the early era of navigation. The man of the sea, has been suffering incessantly the martyrdom of biofouling, and used to laborer scrape for cleaning the hull fouling as the primary palliative.
Two thousand years ago, the wooden hulls of ships were partially covered with lead and painted with mixture of oils infused with of sulfur and arsenic. In 1625, a lethal combination of arsenic, copper and iron powders was considered an important value enough to receive, in England, a patent as an antifouling compound (ANDERSON et al., 2003; PROPELLER, 2002; CLARE, 1995).
Until the first half of the eighteenth century, the most widely used method of combating biofouling of ships remained the drainage or regular scraping to manual docking of living work, a procedure that required tremendous manpower, besides the risk of property damage and lost profits.
There is the record that in 1758, the British frigate HMS Alarm, it was her hull covered with pieces of sheet copper, and that this experiment was considered a success at the time, this procedure by encouraging other ships (CALLOW, 1990).
After the introduction of iron-hulled vessels, the use of copper sheets has been largely discontinued due to problems related to galvanic corrosion, which was virtually ignored at the time. As the main result of this new engineering, has emerged a renewed interest of biocides that could be added to the paints used in painting the hulls of iron.
This perspective has unleashed a flood of products and patents for antifouling compounds, when, in England alone, more than 300 patents have been produced in the late nineteenth century.
In 1860 James Mclnness used copper sulfate as an antifouling. In 1863 James Tarr and Augustus Wonson were receiving a US patent for an antifouling paint that used copper oxide mixed with coal tar naphtha and benzene.
In 1906, the American Navy tested various antifouling paints in the shipyard in Norfolk, Va. As early as 1908 began the production of paints to painting of vivid works of American ships.
Until 1926, some versions of paint were based in mercuric oxide suspended in various resins and solvents. In this same period, the American Navy replaced the paints based on tar, for resin formulations with more fluid consistency of varnish. This came to facilitate the application of the coating as it does not require heating to fluidize the mixture.
In 1940 major changes in paint technology have resulted in a wide range of chemicals products and the introduction of new formulations of surfaces preparations. But the useful life of conventional antifouling paint was still limited because of ignorance of how to control the release of the biocide contained in them.
After the 2nd World War, the emergence of new synthetic resins derived of petroleum, provided paints that has best mechanical properties, which greatly facilitated its implementation. During this time the appearance of organic-tin compounds improved the performance of antifouling paints, so it seemed to have the final answer to such problems (YEBRA et al., 2004).
In 1950 the first record on the broad spectrum of antifouling paints with TBT was made by Van Kerk et al. In the early sixties the excellent property of TBT as antifouling was discovered, making this commercial (YEBRA et al., 2004). While in the seventies many of the antifouling paints were based on the use of copper, the life of these schemes still hovered around 24 months, due to uncontrolled release of biocide used, which increased the cost of repainting and dockings.
The TBT used initially as an adjunct in compound preparations of paints, would become the owner shortly after the lead role, since the development of paint schemes called self-polishing was in progress, and a British patent based upon the composition of TBT with self-polishing copolymer resins obtained by Alexander Milne and George Hails in 1974, revolutionized the industry of the antifouling paints (MILNE and HAILS, 1974). This product has shown excellent control of biofouling and extended the period between dockings. In this combination, the TBT is attached to the polymer-based acrylic through ester links, which are readily hydrolyzed in the slightly alkaline seawater solution (pH ˜8.2), releasing the TBT, which can then act as a biocide. The remaining part of the acid copolymer is solubilized by sea water and then exposes a new layer of TBT-copolymer. This particularity allows to effectively control the release rate of biocide, making its action depending on the paint scheme adopted, can last for up to 5 years (PROPELLER, 1998).
However, in the late seventies, oysters that grew close to ports and marines in the Bay d'Arcachon, France, showed a high incidence of malformation in the shell, which affected their marketing and survival (LEWIS, 2002).
In parallel to advancing the use of TBT, several studies related to its possible environmental damage were performed.
In 1982, Alzieu and colleagues performed experiments keeping oysters in tanks of 150 liters which were successively filled and emptied according to the tide, which contained panels painted in a face with TBT fluoride, at concentrations from 0.2 to 2 μg/L. They found that 30% of oysters died after 110 days of exposure and all died at the end of 170 days (WHO, 1990).
It was estimated that concentrations of up to 100 ng/L of TBT in seawater, it causes significant reductions in the growth of mussels (SALAZAR e SALAZAR, 1996).
Abnormalities of reproductive oysters, Ostrea edulis, were observed after exposure to TBT for 75 days, at a concentration of 0.24 μg/L, a delay in changing sex male to female was observed and larval production was completely inhibited. This phenomenon called “imposex,” which can result in females with a penis, was detailed in the mid-eighties (FERNANDEZ et al. 2002).
As a result, by the end of this decade, countries like France, United Kingdom, United States and Japan, restricted the use of TBT paints. One of the first actions was to ban the use of TBT on vessels that were less than 25 meters in length.
In 1990, the Marine Environment Protect Committee (MEPC) belonging to the IMO adopted a resolution recommending that governments adopt measures to restrict the use of antifouling paints based on TBT.
In November 1999, the IMO Assembly agreed that a set of actions to be taken by MEPC, should ensure a global ban from 1 Jan. 2003, the application of the compounds of organic-tin, which act as biocides in systems of antifouling paint on ships, and a complete ban on the presence of such compounds by 1 Jan. 2008 (PROPELLER, 2000).
Importance of Antifouling
The use of the antifouling painting scheme has as a main purpose to avoid the extra fuel consumption due to additional drag force promoted by excessive fouling the hull of the vessel. It is estimated that the expense relating to the fuel in the shipping industry, is around 50% of the total cost of operation. The annual consumption of heavy oil Bunker type, related to the global commercial fleet, with a price of approximately U$ 100.00 per ton (1998), was estimated at 180 million tons. Biofouling can lead to an increase in fuel consumption of up to 40%, which would increase annual spending in over 7.2 billion dollars. This also implies an increase in a release to the atmosphere of 210 million tons of CO2 and 5.6 million tons of SO2 (PROPELLER, 1998).
A parallel problem to fuel consumption, which draws attention to the need to control biofouling, is the transfer of marine species, components or presents in the biofouling of shells, among the movements of vessels. Although quantitatively smaller compared to transfer of ballast water, organisms transferred by the hooves and anchors are also factors of environmental concern (NRC, 1996).
In Australia, the existing fouling on the hulls of vessels was seen as the main vector of introduction of exotic species in their territorial waters in the late 19th century and throughout the 20th century (Lewis, 2001a, b).
In the United States, the European zebra mussel, Dreissena polymorpha, infested about 40% of waterways of that country, implying spending that, according to some analysts, ranging from hundreds of millions to a billion dollars in control measures between 1989 and 2000 (http://www.great-lakes.net/envt/flora-fauna/invasive/zebra.html).
In New Zealand, research conducted by the National Institute of Water & Atmospheric Research have shown that at least 150 species of marine organisms have been introduced into its waters, and one new species every year, brought by vessels that visits their ports. It is estimated that 69% of the recorded species have been introduced by the hulls of vessels (NIWA, 2002).
In Brazil, the introduction of invasive species Limnoperna. fortunei, known as the golden mussel, was made through the ballast water of vessels that crossed the River Plate Basin. However, the scattering by the Paraguay River and the internal waters have been made mainly by the hull of vessels of different types and sizes.
The proliferation of the golden mussel has caused other problems, like the clogging of pipes and pumps. The observed economic impacts are huge, especially for industries that depends on the uptake of water directly from rivers, lakes and ponds, as dams and water supply companies to urban areas.
Antifouling Systems on Ships
Replacing the TBT
There is no use thinking of shipping, without the use of a defense mechanism against biofouling. Despite the wide range of applicability procedures tested with antifouling applicability, such as: paint base metals like copper and zinc, application of electric current, magnetic fields, radioactive paints with Thallium 204 and Technetium 95, the two most promising alternative systems to the use of TBT are the paint schemes called “fouling-release” and that employ-based paints non-toxic compounds, including natural biocides in this segment (Yebra et. al., 2004).
While some systems “fouling-release” are already available in the market, the development of an efficient product based on natural biocides seems still some way off.
Self-Cleaning System. “Fouling-Release”
The paint system called “fouling-release” can be considered as true non-stick systems, mainly using fluorinated polymers or silicon in their composition (BRADY, 2000). Fluorinated polymers such as polytetrafluoroethylene (PTFE), and the greater difficulty of handling and application, often suffer chemical rearrangements on the surface in contact with polar environments, losing its characteristics of non-wetting, which limits its commercial application. Their uses in the works vivid paintings of vessels need a way to stabilize the surface, and research to eliminate this obstacle is being sought, particularly with the use of semi fluorinated copolymers (Youngblood, 2003, Hayakawa et al. 2000; XIANG et al., 2000).
Systems using silicone are rubbers or elastomers primarily based on polydimethylsiloxane (PDMS) and have been developed since the sixties.
In the United States, Edward Robbart obtained a patent in 1961 (ROBBART, 1961) and Alexander Milne captured another in 1977 (MILNER, 1977). Soon after the patent has been obtained by Milne, the focus of research and development of antifouling turned to the TBT-copolymer systems, another survey of Milne, who at that time was getting a great commercial success. With this, the technology of self-cleaning paints “fouling-release”, was left out (ANDERSON et al., 2003).
In the early eighties, when the environmental problems associated with TBT began to appear, researchers resumed their attention to research programs based on “fouling-release” paints.
These systems are usually free of biocides or in composition with non-toxic, making them environmentally attractive. While allowing the organisms from attaching to the hull when the vessel is stopped, at speeds over 20 knots, occurs the detachment of such organisms leaving the living works free of biofouling.
The performance of such schemes is based on three properties:
a) Surface energy, which controls the ability of a surface to cling to each other. Low-energy produces minimization of the adhesion strength of fouling;
b) The elastic modulus of the painting, which influences the mechanism of the junction between the surface and fouling organisms. Lower elastic modulus values imply weaker adhesions and,
c) Thickness of painting, which is related to the release mode of the body surface. Guests staying exfoliation or peeling.
In general, schemes using fluorinated polymers act by peeling while working by using silicon exfoliation, which requires less energy to occur (LEWIS, 2002; BRADY, 2001e 1999).
Although this system shows high efficiency for high-speed craft, are chemically durable and free of biocides; its cost and its lack of efficacy for vessels of low speed or high speed and with little movement, and fixed structures, have limited its use until the present (PROPELLER, 1998).
Despite the efficiency of the paint schemes currently used, with silicon compounds to be smaller than those containing TBT, much has been researching in such materials because of its apparent non-toxicity and especially its availability. Compounds such as fluorosilicon containing pending groups in fluoroalkyl based on silicone, has demonstrated better self-cleaning characteristics compared to commonly used polysiloxane (GRULAN et al. 2004; MERA and WYNNE, 2001).
Natural products for use as antifouling, obtained from plants, insects and marine organisms have been investigated and several patents have been requested. Henry Hovde and colleagues, received a patent in 2001 which is based on the use of juvenile hormone, found among insects, which demonstrated biocide action against barnacles (HOUVE et al., 2001).
Lars Bohlin and colleagues, received a patent in 2004 that specifies the use of a mixture of peptides of the family “cyclotides,” a new class of proteins extracted from the plant (Viola odorata) http://www.cyclotide.com, which presents beyond well action as antitumoral (LINDHOLM, 2002), a potential action against antifouling barnacles (BOHLIN et al., 2004).
Use of quaternary ammonium compounds (SUSIC, 2004), terpene derivatives (MATIAS, 2001) and vitamins (BONATI, 2001) have also been researched and patented, but not yet marketed.
Nontoxic Compounds
Due to the banning of the antifouling paint schemes using the TBT and the level of environmental pressure over this issue, several theoretically non-toxic products have been incorporated into paints and tested for their actual effectiveness and non-toxicity. Although the antifouling properties of many of the products surveyed are not fully evaluated in the marine environment, many builders and vessel owners have expressed interest in using an non-toxic antifouling paint and which is relatively not expensive, which is reflected application in low cost and high lifetime.
The capsaicin, natural compound non-toxic and irritating, responsible for the burning of black pepper and has been used as an animal repellent, can be effective against aquatic organisms that have a direct contact to the painted substrate (RACE and KELLY, 1994) and research at the University of Akron, Ohio, U.S., have been conducted to evaluate their action as antifouling in the marine environment (NEWBY, 2002).
Laboratory tests using tannins obtained from plants of the genus Mimosa pudica “mimosa”, Castanea dentata “American chestnut” and Schinopsis brasiliensis “quebracho or braun” (STUPAK et al., 2003) and extracts of algae, Bifurcaria bifurcata, and sponge Raspaciona Aculeata, demonstrated to have potential bioactivity against the settlement of larvae of barnacles Balanus amphitrite. 
The trans-8-shogaol compound isolated from the extract obtained from Zingiber officinale “ginger”, and the new sesquiterpene 9-oxo-neoprocurcumenol obtained from Curcuma aromatica “saffron”, traditional herbal medicine of eastern culture, demonstrated a high efficiency against membership mussels “Blue mussel” (ETON et al. 2003 and 2002).
In the search for products that could be used in combating biofouling, it was realized that many marine organisms do not have scale on its surface, while remaining completely under this infliction environment. These marine organisms have developed three main ways of acting against the infliction:
1st) For the tolerance to the invading organism, where it suffers no damage to their vital processes of respiration, nutrition and locomotion;
2nd) At impediment, can make the shift to a less damaging habitat or development of high rates of growth compared to the attacker, without jeopardizing their survival; and
3nd) For the defense itself, which may be mechanical, where surfaces with special structures hinder the settlement; physics, where surfaces with low surface energy prevents the adhesion, and chemical, with the secretion of metabolites harmful to predators or intruders (PEREIRA et al. 2003; ASSMANN et al, 2000; BERENBAUM, 1995, PENNINGS et al., 1994).
The possible chemical compounds released in the defense have generated great interest due to their possible use in the composition of an antifouling paint, and among the major compounds isolated that have antifouling activity are fatty acids, terpenoids, lipoproteins, glycolipids, phenols, lactones, peptides and sterols.
Even in the eighties, several trials have begun to be performed to evaluate the effectiveness of numerous natural products that could come to act as antifouling in marine paints preparation. The main approach has been the solvent extraction of body tissues and subsequent use of bioassays to assess the potential antifouling extracts (WATERMANN, 1997).
In 1981, at the University of Southern California, Backus et al. submerged wood panels impregnated with extracts obtained from marine sponges Haliclona Rubens and Haliclona viridis, to check its pissible antifouling action (BACKUS et al., 1983).
John Faulkner related 841 isolated compounds from marine organisms, in his review on the subject, covering the years from 1977 to 1998. Most of the records it was found metabolites obtained from marine sponges, including a compound called ceratinamine obtained from Pseudoceratina purpurea, had an antifouling action (FAULKNER, 2000, TSUKAMOTO et al., 1996).
In the extract from the marine sponge Acanthella cavernosa, collected on Yakushima Island in Japan, which inhibited the larval settlement and metamorphosis of barnacles Balanus amphritite were found compounds known as diterpenes kalihinenes (OKIN et al. 1995).
Glycerophospholipids Having Antifouling Activity.
In work conducted at the Department of Chemistry, University of Newcastle, Australia, were isolated and identified some lipids present in the extract from the marine sponge Crella incrustans, which showed marked antifouling activity in several clinical trials. These compounds were evaluated by means of RMN, IR and MALDI-MS, as belonging to the class of compounds glycerophospholipids being identical 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine and 1-O-hexadecyl-sn-glycero-3-phosphocholine, glycerophospholipid analogs known as platelet aggregating factor.
The glycerophospholipid known as platelet activating factor is a potent biological mediator produced by various types of cells, which triggers various physiological responses in different cell types even at very low concentrations, 10−12 to 10−9 M (VENABLES et al. 1993, PRESCOTT et al. 1990).
This compound was elucidated simultaneously by groups of teachers Donald Hanahan, Department of Biochemistry, University of Texas, and Fred Snyder, Division of Medical Sciences, Oak Ridge, Institute of Nuclear Studies—Tennessee, which conducted an independent investigation of anaphylaxis in rabbits where platelets were activated, and testing of potential anti-hypertensive rats in a lipid (BLANK et al., 1979). After its structure is understood, a new field of research was opened, primarily targeting medical research (VENABLE et al., 1993).
The factor name aggregating to platelets although incorrectly used, because it describes only one of several effects that this substance causes, remained tied to the chemical structure of the compound being used extensively throughout the literature.
PAF and Lyso-PAF refers respectively to the “1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine,” and “1-O-alkyl-sn-glycero-3-phosphocholine” without bond with the length or degree of unsaturation of the alkyl group, structurally related compounds can be labeled as PAF analogs.
The glycerophospholipids known as platelet aggregating factor shows phylogenetic conservation existing in various positions on the evolutionary scale, being present or being generated in a wide variety of organisms such as bacteria, protozoa, fungi, plants, invertebrates and vertebrates, including mammals. Since its composition in biological samples, consisting mainly of a mixture containing alkyd groups with 16 and 18 carbons in position sn-1 (McINTYRE et al. 1999).
Studies have also shown that PAF analogues such as synthetic glycerophospholipids “1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine,” known as “Et-18-OCH3 or Edelfosine,” promotes a wide range of antitumor activity, and that unlike other drugs, this phospholipid does not affect the DNA of cells under treatment, but acts selectively on the cell membrane, disrupting the metabolism of lipids.
The link type ether present in carbons 1 and 2 make these alkyl-lyso-glycerophospholipid lipases resistant, thus allowing to accumulate in the membrane and other parts of mammalian cells, hindering their development or even taking it apoptosis (VAN DER LUIT et al. 2002; ZHOU et al., 1996).
Besides the compound edelfosine, other alkyl glycerophospholipids and some alkyl-phosphocholine have also presented a cytotoxic action in vivo and in vitro, especially against protozoa, where the studies on such compounds, although not yet fully understood, suppose mechanisms involving damage to the membrane plasma and cell signaling, with the commitment of many cellular metabolism (VERMA and DEY, 2004; PARIS et al., 2004, CROFT et al. 2003; SEIFERT et al., 2001).
Other PAF analogs with radical change in the position sn-1 or sn-2, have also been tested and alkyd radical substitutions in sn-1 by an acyl group and the acetyl radical in the sn-2, for propionyl butiril or have demonstrated a reduction in biological activity of these analogs (TOKAMURA et al. 2000, VENABLE et al., PRESCOTT et al. 1990; TOKAMURA et al. 1989). Similarly, a greater number of methylene groups between the phosphorus atom and nitrogen atom, or the absence of oxygen bound in sn-1 or sn-2, also cause a decrease in activity of these analogues.
The proposed use of such PAF analogues as antifouling agent, based on what happens in other cell types widely used in medicine and pharmacology (MARATHI et al. 2001; BOTITSI et al., 1998, VENABLES et al 1993), based on the possibility of triggering an antagonistic or inflammatory reaction in the cells of the fouling organisms into contact with such products.
Biocidal Activity.
The glycerophospholipids 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine and 1-O-hexadecil-2-O-methyl-sn-glycero-3-phosphocholine have some special properties linked to its molecular structure. They are amphiphilic compounds possess a hydrophilic and a hydrophobic site, and zwitterionic, in example, have positive and negative charges (radical bipolar) in its structure, and also have low molecular weights PM ˜500 Daltons.
These properties are important, when confronted with the EPS diffusion and the potential pathways for uptake by microorganisms. Due to its hydrophobic site, alkyd saturated long chain attached at one end of the molecule, these compounds can be easily absorbed through the lipid bilayer component of the containment cell and plasma membrane of the organisms.
Because they are amphiphilic molecules and have low molecular weight (MW<1000 Daltons), have a good potential to diffuse into the biofilm, and this same feature can also allow passage through a transmembrane protein present in the cell envelope and the plasma membranes, as some these proteins, called Porins have low specificity and generally allow the diffusion of hydrophilic molecules with MW less than 600 Daltons.
Another important factor is that these compounds are PAF analogues without acyl radical type in the sn-2 position, which allows them to act as signaling molecules, when in contact with or absorbed by microorganisms and not suffer the termination of its agonist action of PLA2 enzymes, possibly existing ones. So, unfortunately they will accumulate in the casing wall or inside the cells, triggering an adversarial process of cellular response, which inhibit the development or destroy the microorganism.
Several patent documents describe the use of phospholipids with antimicrobial/antifouling activity.
The document U.S. Pat. No. 4,775,758 describes phospholipids that possess antitumor and antifungal activity, where the phosphate is linked to the central carbon of glycerol.
The document U.S. Pat. No. 5,118,346 describes quaternary ammonium compounds that are useful in antifouling compositions.
The document EP 752 997 describes cationic phospholipids that are useful in the distribution of drugs and nucleic acids in cells containing groups bonded carbon to oxygen of the phosphate group.
The document WO 98/47593 describes compounds that prevent fouling of vinyl monomers in petrochemical refining processes, where the compounds containing groups bonded carbon to oxygen of the phosphate group.
The present invention differs from the compounds mentioned above by an acyl group has only the hydrophobic portion of the molecule and a quaternary ammonium group, linked to the phosphate group.
Thus, the compounds of the present invention are new, facing the prior art, and inventive, by the structure is not even suggested in these documents.